WARNING: suspicious RCU usage in expect_iter_name

Status: upstream: reported C repro on 2026/09/12 00:57
Subsystems: netfilter
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+4bd730aede2791e40bdf@syzkaller.appspotmail.com
First crash: 17h26m, last: 1h44m
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
ca38abda assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING: suspicious RCU usage in expect_iter_name 2026/09/12 00:46 2026/09/12 00:46 2026/09/12 01:18 6816f32e
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH net] netfilter: ctnetlink: fix suspicious RCU usage in expect_iter_name 1 (1) 2026/09/12 01:10
[syzbot] [netfilter?] WARNING: suspicious RCU usage in expect_iter_name 0 (1) 2026/09/12 00:57
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/09/12 00:34 1h24m namangulati@google.com patch bpf error job log

Sample crash report:
=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
net/netfilter/nf_conntrack_netlink.c:3393 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
locks held by syz-executor381/5628: 2, last CPU#1:
 #0: ffffffff9aee42a0 (nfnl_subsys_ctnetlink_exp){+.+.}-{4:4}, at: nfnl_lock net/netfilter/nfnetlink.c:96 [inline]
 #0: ffffffff9aee42a0 (nfnl_subsys_ctnetlink_exp){+.+.}-{4:4}, at: nfnetlink_rcv_msg+0xa69/0x12b0 net/netfilter/nfnetlink.c:293
 #1: ffffffff8ea74d58 (nf_conntrack_expect_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:353 [inline]
 #1: ffffffff8ea74d58 (nf_conntrack_expect_lock){+...}-{3:3}, at: nf_ct_expect_iterate_net+0x38/0x180 net/netfilter/nf_conntrack_expect.c:623

stack backtrace:
CPU: 1 UID: 0 PID: 5628 Comm: syz-executor381 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6972
 expect_iter_name+0xfb/0x100 net/netfilter/nf_conntrack_netlink.c:3393
 nf_ct_expect_iterate_net+0xf2/0x180 net/netfilter/nf_conntrack_expect.c:633
 ctnetlink_del_expect+0x45d/0x640 net/netfilter/nf_conntrack_netlink.c:3455
 nfnetlink_rcv_msg+0xcc2/0x12b0 net/netfilter/nfnetlink.c:300
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 nfnetlink_rcv+0x2b9/0x28c0 net/netfilter/nfnetlink.c:667
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2713
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
 __sys_sendmsg net/socket.c:2799 [inline]
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2802
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb7651a5649
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc2a17f2a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb7651a5649
RDX: 0000000020000080 RSI: 0000200000000300 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000000
R13: 431bde82d7b634db R14: 00007fb765238c40 R15: 0000000000000002
 </TASK>

Crashes (53):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/11 17:57 bpf 15071f2a1263 b6a5eeb7 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 18:55 bpf-next af0b84a9215d b6a5eeb7 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 18:42 upstream 08df884136f1 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/12 01:54 net 784450234395 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 23:39 net 784450234395 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 23:14 net 784450234395 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 22:50 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 21:31 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 21:26 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 21:21 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 21:12 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 20:09 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 20:03 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 19:50 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 19:38 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 19:22 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 17:45 net 784450234395 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 17:15 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:41 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 15:29 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 15:28 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 15:28 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 14:32 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 14:32 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 13:23 net 784450234395 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 12:54 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 12:50 bpf 15071f2a1263 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/12 03:41 bpf-next c1ff425d625e b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/12 00:50 bpf-next c1ff425d625e b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 23:43 bpf-next c1ff425d625e b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 23:41 bpf-next c1ff425d625e b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 23:34 bpf-next c1ff425d625e b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 23:28 bpf-next c1ff425d625e b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 20:21 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 18:06 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 17:29 net-next 348ea4642f56 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:55 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:54 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:46 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:09 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:09 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 16:01 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
2026/09/11 15:53 bpf-next af0b84a9215d b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING: suspicious RCU usage in expect_iter_name
* Struck through repros no longer work on HEAD.